Power over Ethernet (PoE), which is outlined in IEEE Standard 802.3™-2005 clause 33 (the PoE standard), refers to a technique for delivering power and data to an electronic device via Ethernet cabling. In a PoE system, a power-sourcing equipment (PSE) device provides a power supply and data to electronic devices, which may be referred to as powered devices, via twisted pair wires of an Ethernet cable. A powered device is an electronic device that derives its operating power supply and receives data from the same cable. In a particular embodiment, a powered device is a PoE-enabled device. Such powered devices may include voice over Internet protocol (VoIP) telephones, wireless routers, security devices, field devices to monitor process control parameters, data processors, and the like. PoE, broadband over power lines (BPL), and other power/data delivery systems eliminate the need for a separate power source to deliver power to attached powered devices.
Generally, a PSE device includes multiple high-voltage line interfaces to connect to the Ethernet cabling and provides a number of high-voltage functions that include specific protocols and control for safe operations of the high-voltage line interfaces. Often, PSE circuits are used in switches that include multiple line interfaces (typically from four to 192 line interfaces). Typically, each high-voltage line circuit includes control circuitry that performs digital control and timing operations. Such control circuitry is rated for high-voltages and is therefore expensive relative to other low power circuitry.